THE EFFECT OF HYDRAULICALLY CLASSIFIED ULTRA FINE ASH ON MORTAR PROPERTIES

摘要

Hydraulically classified and concentrated ultra fine (D_(50) of 3.0 to 7.4 microns) ash was produced from ponded Class F fly ash from a central Kentucky (USA) power plant. This low calcium ash has excellent pozzolanic reactivity despite being stored for many years. In mortar tests, the ultra fine ash (UFA) had greatly reduced water demand, typically about 10% less than the cement control. The UFA showed accelerated strength development compared to typical Class F and Class C fly ash on both a constant flow and constant water to cement basis at substitution levels of 20% and 40%. Fifty-six day strengths of up to 144% of cement control were recorded. The strength gain was found to be positively relatable to decreasing average particle size. Mortar air entraining admixture requirements were increased with the use of the UFA by factors of 2 to 3 to achieve 16% by volume mortar air.